Russian incursion in Turkish airspace 'unacceptable,' NATO says

The United States and NATO denounced Russia on Monday for violating Turkish airspace along its frontier with Syria, and Ankara threatened to respond if provoked again, raising the prospect of direct confrontation between the former Cold War adversaries.

• Russian military action in Syria a 'terrible mistake,' British PM Cameron says
• Russia bombs Syria targets for 2nd day, including U.S.-backed rebels
• Russia begins air strikes in Syria, U.S. official says
• Should we cry or rejoice as Russia steps up inSyria?

NATO held an emergency meeting in Brussels of ambassadors from its 28 member states to respond to what Secretary-General Jens Stoltenberg called "unacceptable violations of Turkish airspace" after a Russian jet crossed its frontier.

NATO members "strongly protest" and "condemn" incursions into Turkish and NATO territory, the alliance said.

"Allies also note the extreme danger of such irresponsible behaviour. They call on the Russian Federation to cease and desist, and immediately explain these violations," NATO said in a statement after the meeting.

The White House called the Russian move a "provocation," and U.S. Secretary of State John Kerry said it illustrated concerns about an escalated Syrian conflict.

"Had Turkey responded ... it could have resulted in a shootdown, and it is precisely the kind of thing we warned against," Kerry said during a visit to Chile.

The Russian Defence Ministry said on Monday that an SU-30 fighter aircraft had entered Turkish airspace along the border with Syria "for a few seconds" on Saturday.

Moscow's unexpected move last week to launch air strikes in Syria has brought the greatest threat of an accidental clash between Russian and Western forces since the Cold War.

Russian war planes as well as those of the United States and its allies are now flying combat missions over the same country for the first time since World War Two, with Moscow repeatedly targeting insurgents trained and armed by allies of Washington.

Turkish jets harassed

Turkey, a NATO member with the alliance's second biggest army, quickly sent outtwo F-16 jets on Saturday after a Russian aircraft crossed into its airspace near its southern province of Hatay, the Turkish foreign ministry said.

In a second incident, the Turkish military said a MiG-29 fighter an aircraft used both by Russia and Syria had harassed two of its F-16s on Sunday by locking its radar on to them as they patrolled the border.

Turkey summoned Moscow's ambassador to protest against the airspace violation and said Russia would be held "responsible for any undesired incident that may occur" if it were repeated.

Turkish Prime Minister Ahmet Davutoglu earlier said he had been told by Russia that the violation was a "mistake" that would not happen again.

"Turkey's rules of engagement apply to all planes, be they Syrian, Russian or from elsewhere ... Necessary steps would be taken against whoever violates Turkey's borders, even if it's a bird," he said on HaberTurk TV.

"For Russia, which long opposed foreign intervention in Syria and blocked UN Security Council resolutions, to be actively involved in Syria is both a contradiction and a move that has escalated the crisis."

The United States and its allies are waging their own air campaign against Islamic State fighters in Syria, while demanding that Syrian President Bashar al-Assad step down, and supporting other insurgents fighting against him.

Russia says it is targeting ISIS, but the anti-Assad coalition including Washington, European powers, Turkey and most Arab states, say Moscow has mainly targeted other insurgents and hit few ISIS targets.

White House spokesman Josh Earnest said there was no sign Russia had changed its strategy to concentrate on fighting ISIS.

The potential confrontation comes at a time when relations between Russia and the West are at their worst since the Cold War, with the United States and European Union having imposed financial sanctions on Moscow over its intervention in Ukraine.

Over the past year, NATO has repeatedly accused Moscow of sending planes to violate the airspace of the alliance's member countries in Europe.

Speaking during a trip to Spain, U.S. Defense Secretary Ashton Carter compared Moscow's effort to bolster Assad to tethering itself to a sinking ship.

"By taking military action in Syria against moderate groups' targets, Russia has escalated the civil war," Carter said.